/******* 服务器程序  (server.c) ************/
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <sys/time.h>

int main(int argc, char *argv[])
{
	int i, nbytes;
    int sockfd,new_fd;
    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;
    int sin_size,portnumber;
	char sendBuf[]="Hello! Are You Fine?";
	char recvBuf[100];
	struct timeval start, end;

	if(argc!=2)
	{
		fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
		exit(1);
	}

	if((portnumber=atoi(argv[1]))<0)
	{
		fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
		exit(1);
	}

	/* 服务器端开始建立socket描述符 */
	if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)  
	{
		fprintf(stderr,"Socket error:%s\n\a",strerror(errno));
		exit(1);
	}

	/* 服务器端填充 sockaddr结构  */ 
	bzero(&server_addr,sizeof(struct sockaddr_in));
	server_addr.sin_family=AF_INET;
	server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
	server_addr.sin_port=htons(portnumber);

	/* 捆绑sockfd描述符  */ 
	if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)
	{
		fprintf(stderr,"Bind error:%s\n\a",strerror(errno));
		exit(1);
	}

	/* 监听sockfd描述符  */
	if(listen(sockfd,5)==-1)
	{
		fprintf(stderr,"Listen error:%s\n\a",strerror(errno));
		exit(1);
	}

	while(1)
	{
		/* 服务器阻塞,直到客户程序建立连接  */
		sin_size=sizeof(struct sockaddr_in);
		if((new_fd=accept(sockfd,(struct sockaddr *)(&client_addr),&sin_size))==-1)
		{
			fprintf(stderr,"Accept error:%s\n\a",strerror(errno));
			exit(1);
		}

		fprintf(stderr,"Server get connection from %s\n",
				inet_ntoa(client_addr.sin_addr));

		for(i = 0; i < 100; i++){
			printf("Server:%s\n",sendBuf);
			gettimeofday(&start, NULL );
			if(write(new_fd,sendBuf,strlen(sendBuf))==-1)
			{
				fprintf(stderr,"Write Error:%s\n",strerror(errno));
				exit(1);
			}

			if((nbytes = read(new_fd, recvBuf, 100)) == -1){
				fprintf(stderr,"Read Error:%s\n",strerror(errno));
				exit(1);
			}
			gettimeofday(&end, NULL );
			recvBuf[nbytes] = '\0';
			printf("Client:%s\n",recvBuf);

			printf("Intrval: %ldus\n", end.tv_usec - start.tv_usec);
		}
		/* 这个通讯已经结束     */
		close(new_fd);
		/* 循环下一个     */  
	}
	close(sockfd);
	exit(0);
}

